Thinking about jhhdk's submission makes me realize that, for round-rules,
I don't know if this thread has decided how it would handle the situation of
an infinite loop, with each player taking infinitely many full turns
where
1 of the players is taking optional actions and the other is doing nothing
.
Specifically, this could have happened for
jhhdk:
Urza's Mine,
Urza's Power Plant,
Urza's Tower,
Karn Liberated
hypothetical:
Cave-In,
Cave-In,
Pyrokinesis,
Pyrokinesis
.
I will refer to hypothetical as NPD, for "no permanents deck".
NPD can cast Cave-In on T1 and T2, to take a lead in life due to the round rule,
so jhhdk needs to restart the game before jhhdk loses to the round rule.
jhhdk can do that by using Karn's +4 on T3 and T4 and the
ultimate on T5, since jhhdk loses at most 12 life in the meantime.
Karn's rulings state "The player who controlled the ability that
restarted the game is the starting player in the new game.",
so after a restart, jhhdk would lose to the round rule if no one does anything.
Even if NPD still does nothing, the only way jhhdk
can avoid that is by restarting the game again.
This would result in an infinite loop where each player takes infinitely many full turns,
during which NPD is doing nothing and jhhdk is taking optional actions.
Would jhhdk have to break that loop, and thereby lose?